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Midea · Furnace

Pr Incorrect polarity of L1/L2

Medium severity Midea 96% AFUE A2L Gas Furnace (BGH96M)

What the control is telling you

The control detects that line (black) and neutral (white) on the 115 V supply are reversed, or ground is not reliable.

Applies to: Midea BGH96M 96% AFUE two-stage gas furnaces (060B3A, 080B3A, 080C4A, 100C5A, 100D5A, 120D5A)

Likely causes

  • Black and white supply wires swapped at the junction box
  • Poor or missing ground connection to the furnace

Test and repair steps

  1. Warning: Turn off power at the disconnect before touching line-voltage wiring.
  2. Check the field-supplied 115 V wiring in the furnace junction box: black (line) and white (neutral) must match the wiring diagram (Figure 23).
  3. Swap the black and white supply conductors if reversed.
  4. Confirm the supply ground wire is properly and securely bonded to the furnace.
  5. Restore power and confirm Pr has cleared.

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Source: Midea 96% AFUE Gas Furnace (A2L) Troubleshooting Guide, Section 3.6 Pr chart and Fig. 23, p.20. Summarized in our own words; check the original manual for your model.

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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.